In the past two decades there has been a renewed interest in non-petroleum fuels for heating, particularly for domestic use. Many individuals have installed high efficiency stoves that burn wood and wood byproduct fuels, or fireplace inserts for existing fireplaces that increase combustion efficiency, heat distribution, and safety. The use of wood and wood byproducts, which are renewable resources, is apparently a significant step away from reliance on petroleum, which is becoming depleted and will become more expensive. Moreover, wood fuels are produced primarily domestically, whereas oil and natural gas for heating are produced predominantly by offshore sources and are subject to the vagaries of foreign control.
Combustion of wood inherently produces more smoke, soot, and other byproducts that combustion of oil or natural gas. Thus an unfortunate side effect of increased use of wood for domestic heating is an increase in air pollution. In some communities where many individuals have adopted wood-fired heating systems, there is a noticeable degradation in air quality during the winter heating season. Indeed, some communities have had to limit wood-fired heating systems to meet minimum air quality standards set by state and federal regulations.
Another disadvantage of the use of wood-burning stoves and fireplaces is the release of sparks and cinders from the chimney. These hot particles are capable of starting roof fires, especially on wood shake roofs, and also setting fire to surrounding vegetation such as trees, dry grass, and the like. Most communities require spark arresters atop the chimney, but their effectiveness can be affected by high winds, low humidity, and the type of fuel being burned.
There are known in the prior art many forms of smoke scrubbers and stack gas scrubbers. One example is U.S. Pat. No. 5,395,408, issued Mar. 7, 1995 to the present inventor. These devices generally treat smoke and gas from a flue by washing the flue gases with water or an aqueous solution. The flue gases may be driven by blower through a tank containing the aqueous solution, so that the gas bubbling through the liquid is cooled, hot particles are extinguished, and particulates are picked up by the liquid. However, the blower itself can cause noise and vibration inside the dwelling, which may be objectionable to some persons.